Color cathode ray tube with metallic contactor ribbon bonded on inside wall of tube between the high voltage terminal and the shadow mask frame



Nov. 24, 1970 Filed April 16, 1969 W. H. M NEILL COLOR CATHODE RAY TUBEWITH METALLIC CONTACTOR BONDED ON INSIDE WALL' OF TUBE BETWEEN THE HIGHIll VOLTAGE TERMINAL AND THE SHADOW MASK RIBBON ATTORNEY Nov. 24, 1970w. H. M NEILL 3,543,072

COLOR CATHODE RAY TUBE WITH METALLIC CONTACTOR RIBBON BONDED ON INSIDEWALL OF TUBE BETWEEN THE H IGH VOLTAGE TERMT AL AND THE SHADOW MASKFRAME Filed April 16, 1969 2 Sheets-Sheet 2 I 54 k 1 \\\l 7 32 zs KdPZZINVENTOR. WILLIAM H. Me NEILL United States Patent US. Cl. 313-85 4Claims ABSTRACT OF THE DISCLOSURE In glass color cathode ray tubes ameans for applying the high voltage to the shadow mask frame whichcomprises welding or otherwise fixing one end of an electricallyconductive metallic ribbon directly to the second anode button andforming the other end as a spring to contact the shadow mask frame.Intermediate the welded end and the spring formed end the ribbon is fritsealed to the interior surface of the tube wall. Alternatively, theother end of the ribbon may be formed as a broadened spring contactingportion and a conventional, although much stronger contact spring may beutilized therewith.

BACKGROUND OF THE INVENTION This invention relates to electricalcontactors and more particularly to contactors for achieving anelectrically conductive path from the second anode or high voltage leadof a glass cathode ray tube to the shadow mask frame thereof.

Current cathode ray tubes for the reproduction of color images comprisean all glass envelope formed from two major pieces; namely, afunnel-shaped body and a face panel.

The face panel is generally dish-shaped with an upstanding peripheralwall. The screen of the tube, which comprises a pattern of differentcolored light emitting phosphors, is disposed on the interior surface ofthe face panel. A shadow mask assembly, comprised of a relativelyfragile foraminated structure attached at its peripheral edge to arelatively rigid frame, is supported Within the face panel by means ofsprings attached to the sides of the frame and studs attached to theinside surfaces of the panel walls.

After the screen is formed the face panel is sealed, as by a glass frit,to the wide end of the funnel-shaped body. The narrow end of the funnelis formed to provide a cylindrical neck which receives the one or moreelectron guns necessary to energize the phosphors to luminescence.

For the electrons emitted from the guns to achieve a sufiicient velocityto correctly excite the phosphors the final anode electrode of the gunshas applied thereto a relatively high voltage in the neighborhood of 25kv. For proper operation of the tube it is desirable that this voltagealso be applied to the shadow mask, usually via the frame. To accomplishthis, current tubes utilize an electrically conductive coating, usuallyAquadag, on the interior surface of the funnel. One end of the coatingextends into the neck of the tube and the other end to a positionclosely adjacent the panel seal area. Snubbers on the final anode of thegun or guns contact the coating in the neck and thus apply the voltagethereto.

While the various voltages necessarily fed to the other electrodes ofthe guns are carried via pins formed at the terminus of the neck, thehigh voltage is applied to the coating by means of an electricallyconductive metallic button which is hermetically sealed in a wall of thefunnel. A suitable source of high voltage is provided in the televisionreceiver and is connected to the button by any suitable means.

3,543,072 Patented Nov. 24, 1970 A contact spring attached to the frameextends upwardly into the funnel and provides the electrical path to thecoating. Numbers of contacts for achieving the abovedescribed path areknown in the art. However, problems exist with all known forms. One ofthe major problem areas exists in relation to shock resistance; i.e.,under mechanical shock and the subsequent vibrations therefrom beingpassed onto the contact spring, electrical contact is momentarily lostbetween the conductive coating and the frame, resulting in a temporaryloss of picture. In an attempt to counteract this eifect the springshave been formed of a heavier material to exert greater force upon theconductive coating. This technique introduces other problems however, inthat the heavier springs tend to chip olf the conductive coating. Whenthe coating is chipped away enough contact may permanently be lost,resulting in an inoperative tube.

Plural identical contacts have also been used, spaced around the frame,but this approach has proven unacceptable since it increases the costand does not solve the problem.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore, an object of thisinvention to obviate the disadvantages of the prior art.

It is another object of the invention to enhance the operation of colorcathode ray tubes.

It is a further object of the invention to improve the high voltage toshadow mask frame electrical connections in color cathode ray tubes.

These objects are accomplished in one aspect of the invention by theprovision, in a color cathode ray tube of means for providing a directelectrical path from the high voltage lead to the frame. The meanscomprises a metallic, electrical conductive ribbon aflixed at one end tothe high voltage lead and at its other end being formed to provide anelectrical path to the frame.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a colorcathode ray tube illustrating an embodiment of the invention;

FIG. 2 is a sectional view illustrating an alternate embodiment of theinvention; and

FIG. 3 is a view of the embodiment of FIG. 2 taken along the line 33 ofFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding ofthe present invention,

together with other and further objects, advantages and capabilitiesthereof, reference is made to the following disclosure and appendedclaims in connection with the above-described drawings. Referring now tothe invention with greater particularity, there is shown in FIG. 1 adiagrammatic sectional view of a type of cathode ray tube 10 utilizedfor the reproduction of polychrome images, as in color televisionreceivers. The tube 10 has an eletrically insulating funnel-shaped body12, as of glass, with a dish-shaped face panel 14 also of glass sealingthe wide end thereof and a cylindrical neck 16 sealing the narrow end. Aglass frit is generally utilized to form the panel to body sealdesignated in the drawings as 17.

A cathodoluminescent screen 18 is formed on the interior surface of facepanel 14 and comprises a patterned array of different colored lightemitting phosphors. An electron source 20, which may comprise one ormore electron guns, is positioned in the neck 16.

To aid in color selection there is provided adjacent the screen a shadowmask assembly 22 which comprises a foraminated portion 24 supported atits peripheral edge 26 by a relatively rigid frame 28. The assembly 22is sup ported within the face panel 14 by means of cooperation between aplurality of springs 30 (only one of which is shown) mounted on a wallof the frame 28 and a like number of studs 32 mounted on a well 34 ofthe face panel 14.

During operation of the tube various potentials are applied toelectrodes of the guns by means of lead pins which extend through theterminus of the neck 16 and which are appropriately connected to theelectrodes. This is conventional in the art and the lead pins are notillustrated in the drawings.

The electrical connection to the final anodes of the guns is achievedthrough a wall of body 12 by means of an electrically conductive,metallic button 36, which is hermetically sealed in the wall, and anelectrically conductive coating 38 which is applied to the interiorsurface of the body and extends into the neck area and to a pointclosely adjacent the panel seal 17. Metallic snubbers 40 electricallyconnected to the final anodes 41 also contact the coating 38 to completethe electrical path thereto.

To achieve the electrical connection to the shadow mask frame there isprovided means 42 in the form of an electrically conductive metallicribbon 44 afiixed at one end 46 to the button 36, as by welding, andwhich has its other end 48 formed to provide an electrical path to theframe. At least portions of ribbon 44 are frit sealed to the inner wallsurface of body 12 and to insure continuity of the coating 38 thisshould be done prior to the application of the coating 38.

The end 48 of ribbon 44 may be formed as a contact spring 50 as shown inFig. 1 or it may be formed as a broadened area 52 as is shown in FIGS. 2and'3. When the latter embodiment is utilized one or more conventionallyshaped springs 54 attached to the frame contact the broadened area 52;these springs however, may be considerably more powerful than those usedheretofore since there is no danger of contact loss because of erosionor chipping away of the coating 38.

Thus it will be seen that there is herein provided new and novel meansof providing a direct electrical path for the high voltage to the shadowmask frame of a color cathode ray tube. The various embodiments areextremely rugged and obviate the diadvantages inherent in the prior artstructures.

While there have been shown and described what are at present consideredthe preferred embodiments of the 4 invention, it will be obvious tothose skilled in the art that various changes and modifications may bemade therein without departing from the scope of the invention.

I claim:

1. In a color cathode ray tube having a body formed from an electricallyinsulating material, a cathodoluminescent screen and a shadow maskassembly comprising a foraminated portion and a rigid frame supportedadjacent said screen, an electrically conductive coating on the interiorof said envelope and an electrically conductive button hermeticallysealed in said insulating body, the improvement comprising: means forproviding a direct electrical path from said conductive button to saidframe, said means comprising a metallic, electrically conductive ribbonbeneath said conductive coating and affixed at one end to said buttonand at its other end having an electrical path to said path.

2. The invention of claim 1 wherein at least the intermediate portion ofsaid ribbon is bonded to the interior surface of said body.

3. The invention of claim 2 wherein said other end of said ribbon is aframe contacting spring.

4. The invention of claim 2 wherein said other end of said ribbon is abroadened area bonded to said interior surface of said body and saidelectrical path is a contact spring attached at one of its ends to saidframe and at the other of its ends to said broadened area.

References Cited UNITED STATES PATENTS 2,820,166 1/1958 Pinotti 313642,863,084 12/1958 Arnott et al. 313-64 X 2,950,408 8/1960 Ketchpel 31364X 2,951,179 8/1960 Evans 31392 3,102,212 8/1963 Schlesinger 313- X3,404,303 10/1968 Levin 31385 ROY LAKE, Primary Examiner V. LAFRANCHI,Assistant Examiner US. Cl. X.R.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,543,072 Dated November 24, 1970 Inventor) William H. McNeill It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

column 3, line 3 of the specification "well" should read--wa1l-.

Column 4, line 17 of Claim 1 "path" should read--frame yl uu Gomlaaioner0 Patents

